# Scientific Calculator Plus 991 — NCalc & CalcES Calculator 115

> Scientific calculator, graphing tool, and unit converter for students and professionals. (iPhone/iPad app by Tran Duy.)

- Source: https://appshunter.io/ios/app/scientific-calculator-plus-991/id1449106995 (this page in markdown: same URL + `.md`)
- Developer: [Tran Duy](https://appshunter.io/developer/1449106994)
- Category: Education, Productivity
- Price: Free with in-app purchases
- Rating: 4.70/5 from 12,288 App Store ratings · 498 written reviews indexed
- Age rating: 12+
- Requires: iOS 15 · 176 MB
- Languages: American English, Albanian, Arabic, Armenian, Azerbaijani, Basque, Belarusian, Bangla, Bosnian, Bulgarian and 41 more
- Released: 2019-04-03
- Data updated: 2026-08-27
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/scientific-calculator-plus-991/id1449106995/reviews.md

## What is Scientific Calculator Plus 991?

NCalc — Powerful Scientific Calculator, Graphing, and Converter

NCalc combines a natural-display scientific calculator, advanced math tools, a full graphing module (as 83/84 calculator), a large formula library, and a comprehensive unit and currency converter—designed for students, engineers, and anyone who loves math.

◉ Main Calculator Features
- Natural display: Enter expressions exactly as in textbooks—fractions, roots, exponents, and more—see results as written on paper.
- Keyboard layout: Matches popular models for familiarity and speed: 115 ES Plus, 991 ES Plus, 300 ES Plus, and 991 EX.
- Symbolic and numeric modes: Perform exact fraction calculation or evaluate numerically when needed.
- Arbitrary precision integers: Work with very large integers without losing accuracy.
- Output types: Choose from fraction, mixed fraction, decimal, repeating decimal, degrees/minutes/seconds, and polar coordinates.
- Angle units: Degree, radian, and gradian (grade).
- Decimal formatter: Display numbers in normal, engineering, engineering SI, scientific, or fixed formats.
- Calculation history: Review and reuse past calculations with ease.
- Copy and paste support for fast data entry and sharing.

◉ Algebra, Calculus, and Core Math
- Algebra calculation: Expansion, factorization, simplification, and more.
- Calculus calculator: Derivatives, integrals, and limits of expressions.
- Complex number calculation: Arithmetic, polar/rectangular conversion, exponential, logarithm, powers, roots, and full trigonometric functions.

◉ Equations and Inequalities
- Equation solver: Solve general equations, plus dedicated solvers for quadratic, cubic, and quartic equations.
- System of equations solver: Solve systems with 2, 3, or 4 variables.
- Inequality solvers: Quadratic, cubic, and quartic inequalities with interval-based solutions.

◉ Matrices and Vectors
- Operations: Addition, subtraction, multiplication for matrices and vectors.
- Advanced tools: Determinant, inverse, transpose, rank, eigenvalues, and eigenvectors.

◉ Statistics and Distributions
- Statistical calculation: Descriptive stats and regression calculation (including a regression plotter).
- Distribution calculation: Normal distribution, binomial distribution, Poisson distribution, t-distribution, chi-square distribution, and F-distribution.

◉ Number Bases and Formats
- Base N calculation: Effortlessly switch between binary, octal, decimal, and hexadecimal, with arithmetic in each base.

◉ Tables, Variables, and Custom Functions
- Table Generator: Generate value tables based on any expression and range.
- Calculator variables: Store values and reuse them across calculations.
- User-defined functions: Create your own functions to streamline repetitive work.
- Built-in constants: A rich set of mathematical and physical constants.

◉ Formulas
- Extensive formula collection: Math and Physics formulas, clearly categorized—ideal for secondary school, high school, and university students.

◉ Unit Converter
- Currency Converter
- 1000+ unit conversions

◉ Graphing as 83, 84 calculator
- Cartesian functions, implicit plots, polar, and parametric.
- Tracing, roots, intersections, extrema, derivative, and integral evaluations on graphs.

◉ Auto-renewing subscription
You may purchase an auto-renewing subscription through an In-App Purchase.
• Auto-renewable subscription
• Your subscription will be charged to your AppStore account at confirmation of purchase and will automatically renew (at the duration selected) unless auto-renew is turned off at least 24 hours before the end of the current period.
• Current subscription may not be cancelled during the active subscription period; however, you can manage your subscription and/or turn off auto-renewal by visiting your AppStore Account Settings after purchase
• Privacy policy and terms of use: https://ncalc-app.web.app/terms-of-services.html

## Key features

- Natural display input
- Graphing module
- Formula library
- Unit and currency converter
- Algebra and calculus tools
- Matrix and vector operations
- Statistical calculations

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Calculator yearly subscription | $3.99 | per year |
| Calculator month subscription | $1.99 | per month |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Calculator Premium | $5.99 | one-time |
| Calculator Pro | $5.99 | one-time |


## What do users think of Scientific Calculator Plus 991?

Overall sentiment: positive

**Pros**

- 👍 Intuitive and easy to use
- 🚀 Powerful and feature-rich
- 💡 Customizable interface and settings
- 🔍 Extensive library of formulas and equations
- ⚙️ Handles complex math and scientific functions well
- 🧠 Helpful for STEM students and professionals

**Cons**

- 🐛 Occasional bugs and input issues
- 🔀 Confusing layout and button placement
- 💰 Some advanced features locked behind paywall

**Commonly reported bugs**

- Keyboard input stops working after switching screens
- Incorrect calculation results for certain operations
- App crashes on some devices after recent update

**Most requested features**

- Add option to change display font and color
- Improve cursor control and editing capabilities
- Implement auto-simplification for complex expressions
- Add more handwriting font options
- Expand graphing and equation solving features

## Recent user reviews (10 of 498)

All indexed reviews: https://appshunter.io/ios/app/scientific-calculator-plus-991/id1449106995/reviews.md

### 5/5 — It helped me so much with my English assignment!! So good!

*2026-08-10, version 3.6.1*

So basically I had a task to write a story about a bear, and I wanted to write about Winnie the Pooh. I planned this splendid story about how Winnie needed honey and then asked Piglet for some.  It the thing was, I did not know how to spell delishous! Well, I downloaded this calculator and it helped me spell it, and even gave me tips on how to improve my story! Thanks to it, I now know that delishous is spelled with an sh and not a c, like I previously though. This app is super ⭐️⭐️⭐️⭐️⭐️

### 4/5 — It’s good, but there needs to be a fix.

*2026-08-09, version 3.6.1*

The “*10^n” part beyond 10^10^20 needs to be inside the exponent, not outside.

### 4/5 — Good app but I wish there was dark mode icon

*2026-08-06, version 3.6.1*

I like this app, but I wish there was a dark mode icon

### 5/5 — Brilliant Scientific Calculator

*2026-07-26, version 3.6.1*

Fantastic tool for study and everyday practice. Still exploring its numerous modules (or features).

### 5/5 — Like it!

*2026-07-23, version 3.6.1*

It has awesome features!

### 5/5 — calc

*2026-07-20, version 3.6.1*

good

### 5/5 — Very helpful app

*2026-07-17, version 3.6.1*

I’ve been using this calculator app for a while now, and it has been really helpful. It’s fast, simple, and does exactly what I need without any hassle. Definitely deserves 5 stars!

### 1/5 — ads

*2026-07-14, version 3.6.1*

i’m seeing half naked girls as ads like wtf

### 5/5 — Best

*2026-07-13, version 3.6.1*

Best digital calculator with maths photo solution

### 5/5 — Great

*2026-07-08, version 3.6.1*

Works great

## Frequently asked questions about Scientific Calculator Plus 991

### What does NCalc Scientific Calculator + do?

NCalc is a comprehensive scientific calculator that includes a graphing module, a large formula library, and a unit and currency converter. It is designed to assist students, engineers, and math enthusiasts with a wide range of mathematical tasks.

### What are the key features of this calculator app?

Key features include a natural display for entering expressions as they appear in textbooks, a graphing module similar to popular graphing calculators, advanced tools for algebra, calculus, matrices, and statistics, and a built-in unit and currency converter. It also supports multiple number bases and provides a calculation history.

### Is NCalc Scientific Calculator + free to use?

The application is available for free download and use, but it does contain in-app purchases. This means that while the core functionality is accessible, certain advanced features or content may require a purchase to unlock.

### Who is the target audience for NCalc Scientific Calculator +?

This app is primarily designed for students, engineers, and anyone with a strong interest in mathematics. Its extensive features cater to users who require advanced calculation, graphing, and problem-solving capabilities for academic or professional purposes.

### What kind of math problems can this app solve?

The app can handle a wide array of mathematical problems, including algebraic manipulations (expansion, factorization), calculus operations (derivatives, integrals, limits), solving various types of equations and inequalities, matrix and vector operations, and statistical calculations. It also supports complex number arithmetic and number base conversions.

## Version history (last 5 releases)

### 3.6.1 — 2026-06-25

Thanks for using NCalc! This update includes performance improvements, stability enhancements, bug fixes, UI refinements, and compatibility updates for the latest iOS versions to ensure a smoother, more reliable experience.

### 3.5.8 — 2026-05-05

Thanks for using NCalc! This update includes performance improvements, stability enhancements, bug fixes, UI refinements, and compatibility updates for the latest iOS versions to ensure a smoother, more reliable experience.

### 3.5.7 — 2026-04-19

Thanks for using NCalc! This update includes performance improvements, stability enhancements, bug fixes, UI refinements, and compatibility updates for the latest iOS versions to ensure a smoother, more reliable experience.

### 3.5.6 — 2026-02-10

What's new in this version:
- Math OCR now supports drawing for easier input.
- Option to hide the button in the calculator display.
- Bug fixes and performance improvements for a smoother experience.

Thanks for using NCalc!

### 3.5.5 — 2026-02-06

What's new in this version:
- Math OCR now supports drawing for easier input.
- Option to hide the button in the calculator display.
- Bug fixes and performance improvements for a smoother experience.

Thanks for using NCalc!

## Apps similar to Scientific Calculator Plus 991

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## More apps by Tran Duy

- [Ncalc - Graphing Calculator 84](https://appshunter.io/ios/app/ncalc-graphing-calculator-84/id1509489130)

All apps by Tran Duy: https://appshunter.io/developer/1449106994

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-27.*